A. Field of the Invention
The present invention generally relates to electrodes/electrode tips and ablation systems. Aspects of the invention involve catheter-based ablation systems useful for ablating biological tissue, including the treatment of heart conditions. More particularly, the present invention includes electrodes/electrode tips and insulated catheter ablation systems for use in epicardial procedures, such as those used for the treatment of atrial fibrillation or ventricular tachycardia.
B. Background Art
Catheters have been in use for medical procedures for a number of years. For example, one procedure, often referred to as “catheter ablation,” utilizes a catheter to convey energy to a selected location within the human body. Another procedure oftentimes referred to as “mapping” utilizes a catheter with sensing electrodes to monitor various forms of electrical activity in the human body.
Moreover, catheters are increasingly used for medical procedures involving the human heart, including the treatment of certain types of ventricular arrhythmia and atrial arrhythmia. Such procedures commonly involve the ablation of tissue in the heart and are performed many times with an ablation catheter. Ablation catheters are commonly inserted in an artery or vein in the leg, neck, or arm of the patient and threaded, sometimes with the aid of a guidewire or introducer, through the vessels until the distal tip of the ablation catheter reaches a desired location for the ablation procedure. The ablation catheters commonly used to perform such procedures often electrically isolate or render the tissue non-contractile at particular points by physical contact of the tissue with an electrode of the ablation catheter and the application of energy.
In some conventional ablation procedures, the ablation catheter includes a single distal electrode secured to the tip of the ablation catheter to produce small lesions wherever the tip contacts the tissue during energy application. To produce a linear lesion, the tip may be dragged slowly along the tissue during energy application. Increasingly, however, cardiac ablation procedures utilize multiple electrodes affixed to the catheter body to form multiple lesions.
Traditional ablation electrodes provide an electrically conductive surface on the entire surface of the electrode, thereby potentially ablating surfaces of surrounding tissue, in particular, the pericardial sac when attempting to ablate the epicardial surface of the heart. Another challenge in obtaining an adequate ablation treatment using conventional ablation catheters is the constant movement of the heart, particularly when there is an erratic or exhibits an irregular heart beat. Another challenge in obtaining an adequate ablation treatment is associated with the inability of conventional catheters to obtain and retain sufficient contact with target tissue along or across various tissue surfaces.